In FIG. 29 and FIG. 30, a male terminal and female terminal to which a conventional contact-connection structure has been applied are shown (see Patent Literature 1 as an analogous art).
As shown in FIG. 29, FIG. 30 and FIG. 31, a female terminal 1051 has a quadrilateral box part 1052, and an elastic deflection part 1053 that is provided integrally with this box part 1052 and is arranged in the box part 1052.
The elastic deflection part 1053 is provided with an indent part 1054 that projects toward the bottom surface side.
The indent part 1054 is almost spherical in shape of its outer circumference surface thereof and the central top is situated at the lowermost part.
Note that, although in FIG. 29 and FIG. 30, illustration is omitted, plating (for example, tin plating) is performed on the entire area of an outer surface of the female terminal 1051 and a plated layer is provided from the viewpoints of improvement of connection reliability under a high-temperature environment, improvement of corrosion resistance under a corrosive environment and so forth.
As shown in FIG. 29, FIG. 30 and FIG. 32, a male terminal 1060 has a tabular tab part 1061.
Note that, although in FIG. 29 and FIG. 30, illustration is omitted, plating (for example, tin plating) is performed on the entire area of an outer surface of the male terminal 1060 and a plated layer is provided from the viewpoints of improvement of the connection, reliability under the high-temperature environment, improvement of the corrosion resistance under the corrosive environment and so forth.
When plating (tin plating) is performed as described above, and then a reflow process is performed, a plated layer (a copper/tin alloy layer, a tin-plated layer) is formed on the outer surface side of a base material of a copper alloy material, and an oxide film is formed on an outer surface of the plated layer.
In the above-mentioned configuration, when the tab part 1061 of the male terminal 1060 is inserted into the box part 1052 of the female terminal 1051 at a position in FIG. 29, the elastic deflection part 1053 deflectively deforms and insertion of the tab part 1061 is allowed.
In an insertion process of the tab part 1061, the indent part 1054 of the elastic deflection part 1053 slides on a contact surface 1061a of the tab part 1061, and at a terminal insertion completion position, as shown in FIG. 30 and FIG. 33, the indent part 1054 of the elastic deflection part 1053 and the contact surface 1061a of the tab part 1061 come into contact with each other.
As described above, when the indent part 1054 slides on the contact surface 1061a of the tab part 1061, deflection restoring force of the elastic deflection part 1053 acts as a contact load and thereby, as shown in FIG. 35A, FIG. 35B (illustration of a plated layer, an oxide film formed on the indent part 1054 is omitted), an oxide film formed on the indent part 1054 is destroyed, and a plated layer 1063 formed on the tab part 1061 is pushed into it and thereby an oxide film 1064 is destroyed.
When each oxide film 1064 is destroyed in this way, metal (for example, tin) for plating spouts out of a crack in each oxide film 1064 and thereby the indent part 1054 of the female terminal 1051 and the contact surface 1061a of the tab part 1061 of the male terminal 1060 electrically come into contact with each other.
That is, the indent part 1054 of the female terminal 1051 and the contact surface of the tab part 1061 of the male terminal 1060 electrically come into contact with each other, using the deflection restoring force of the elastic deflection part 1053 as the contact load.
Them an electric current flows through a contact surface between the indent 1 part 1054 and the tab part 1061 and thereby the female terminal 1051 and the male terminal 1060 are conducted.
Note that the oxide film 1064 is very high in electric resistance in comparison with tin and copper. Accordingly, in order to reduce contact resistance, it is necessary to destroy the oxide film 1064 so as to form many plating-to-plating contact surfaces (ohmic contact points).
In a conventional contact-connection structure, the oxide film is destroyed by the contact load between the indent part and the contact surface of the tab part so as to obtain a contact between plated metals of the indent part and the tab part at a destroyed spot of the oxide film.